Prevalence and molecular characterization of Clostridium difficile isolated from feedlot beef cattle upon arrival and mid-feeding period

Clostridium difficile was isolated from 18 of 539 animals at the time of feedlot arrival (CI = 2.3-6.1) and from 18 of 335 cattle at mid-feeding period (CI = 2.9-13.1). Overall, there was no significant difference in the prevalence of C. difficile shedding on arrival versus mid-feeding period (P = 0.47). No association between shedding of the bacterium and antimicrobial administration was found (P = 0.33). All the isolates recovered were ribotype 078, a toxinotype V strain with genes encoding toxins A, B and CDT. In addition, all strains were classified as NAP7 by pulsed field gel electrophoresis (PFGE) and had the characteristic 39 base pairs deletion and upstream truncating mutation on the tcdC gene.It is apparent that C. difficile is carried in the intestinal tracts of a small percentage of feedlot cattle arriving and later in the feeding period and that ribotype 078/NAP7 is the dominant strain in these animals. Herd management practices associated with C. difficile shedding were not identified, however further studies of the potential role of antimicrobials on C. difficile acquisition and shedding are required.Clostridium difficile is a Gram-positive, spore-forming bacterium responsible for C. difficile infection (CDI) in humans [1], a serious and increasingly problematic disease. A remarkable change in the epidemiology of CDI has been encountered over the past 10 years, with increasing incidence, mortality and relapse rates in humans [2,3]. Additionally, while classically a hospital-associated pathogen predominantly affecting elderly individuals, there are increasing reports of community-associated CDI, including disease in younger individuals and people with few or no traditional risk factors [1,4,5].The source of infection for community-associated cases of CDI remains uncertain, however foodborne infection has been suggested [4]. Indeed, several studies have recovered spores of C. difficile from food products including retail meat [6-9], yet the source of con